It's almost as if Adobe have no motives whatsoever to make the proprietary file format for their cash cow easy to use for those who would like to build competing products.
Like Adobe's tools are often improved but, it feels like from a user's perspective, that they're stacking kludge on kludge (similar to Oracle DB or Microsoft's Outlook).
This may be unfair, for all I know Photoshop has a great codebase, but the bugs I've seen and experienced give me a bad impression.